• Membrane Journal
• /
• v.26 no.3
• /
• pp.212-219
• /
• 2016

The alumina hollow fiber membranes were prepared by spinning and sintering a polymer solution containing suspended alumina powders. For determine pore structure of hollow fiber membranes formed by different solvent-nonsolvent interaction rate, dimethylsulfoxide (DMSO), dimethylacetamide (DMAc), triethylphosphite (TEP) were prepared in dope solution by solvent, polyethersulfone (PESf) and polyvinylpyrrolidone (PVP) were used as a polymer binder and additive. The pore structure of hollow fiber membranes was characterized using scanning electron microscope (SEM). The alumina hollow fiber membranes prepared by DMSO, DMAc were had the asymmetric structure mixed sponge-like and finger-like morphology, while TEP solvent were had single sponge-like structure. The prepared hollow fiber membranes were analyzed gas permeation and mechanical strength experiment also. The hollow fiber membrane having single sponge-like structure was had high gas permeation performance. On the contrary to this, more finger-like morphology was less gas permeation performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.1
• /
• pp.145-149
• /
• 2023

High-resolution images of surfaces provide detailed information on pores or shapes with specific sizes ranging from nano sizes to micrometers. However, it is not yet clear to determine an efficient association for pores or shapes from high-resolution images of surfaces. For the efficient association of pores and shapes, the surface characteristics of the device were considered as fractal dimensions by taking SEM photographs and binarizing the images. The fractal program was directly coded for surface analysis of the device. The device surface characteristics and electrical characteristics are thought to be related to the fractal dimension. The fractal dimension decreased with an increase in internal pores. The density and grain boundary of particles, which are structural characteristics of the device surface, were related to the fractal dimension. The particle size decreased with an increase in the fractal dimension and was uniformly formed. When the particles were uniformly formed, fewer pores were present and the fractal dimension increased.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2018.06a
• /
• pp.93.1-93.1
• /
• 2018

그래핀 에어로겔은 우수한 전기 열 전도도, 기계적 특성, 넓은 표면적으로 베터리, 약물방출 등 다양한 분야에서 많은 연구가 진행되고 있다. 특히, 그래핀 에어로겔은 친수성, 생체안전성, 삼차원구조의 특성으로 우수한 약물방출형 임플란트 소재로의 활용이 기대된다. 본 연구에서는 그래핀 산화물의 수열처리를 통해 그래핀 하이드로겔 형성 후, 저온건조와 동결건조를 이용하여 그래핀 에어로겔을 제조하였다. 그래핀 산화물과 그래핀 에어로겔의 특징들을 XRD, SEM, XPS, Raman등을 통해 확인하였으며, 그래핀 에어로겔에서 건조방법과 건조시간에 따른 기계적 강도, 기공구조의 제어가능성을 BET, SEM등의 분석을 통해 확인하였다. 이러한 기공구조 제어를 통해 약물방출 특성을 측정하였으며, 인체 삽입형 임플란트로서의 활용 가능성을 확인할 수 있었다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1994.06b
• /
• pp.35-48
• /
• 1994

본 연구는 윤활시스템용 오일필터로서 개발된 자성폴리머 필터의 충진밀도에 따른 여과특성을 조사하기 위해 유속, 여과시간 및 자성유무 등의 변수를 변화시키면서 실험실적 방법으로 행해졌으며 다음과 같은 결과는 얻었다. 1. 자성폴리머 필터의 충진밀도가 증가함에 따라 여과효율 및 압력손실은 증가하는 경향을 나타내고 있으며, 이는 자성폴리머 필터의 기공 및 자성에 그 원인이 있다. 2. 자화 및 비자화된 자성폴리머 필터의 압력손실은 동일한 경향을 나타내고 있으나 여과효율은 현저한 차이를 나타내었다. 이는 자성의 영향에 의존함을 알 수 있다. 3. 자성폴리머 필터는 기존의 종이 필터보다 우수한 여과특성을 나타내고 있으며, 이는 다른 여과 메카니즘에 기인한다. 즉 종이 필터는 단지 기공에만 의존하는 표면여과방식인 반면 자성폴리머 필터는 기공(Porosity)과 자력(Magnetic Attration)의 기능을 지닌 심층여과 필터와 자성필터의 두기능을 지니기 때문이다. 따라서 개발된 자성폴리머 필터는 실제 윤활시스템에 적용시 매우 효과적인 오일필터로 작용 할 것으로 사료된다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1996.04b
• /
• pp.55-57
• /
• 1996

본 연구에서는 용사코팅재료의 용사기법에 따른 용가코팅층의 기계적 물성을 파악하고 SM48C 고주파 경화 시편과 용사코팅재료와의 고하중, 고속 윤활상태에 따른 슬라이딩 마멸특성을 파악하고자 하였다. Fe-Cr-B의 용사코팅 공정표면의 경도와 기공율이 슬라이딩 마멸거동에 큰 역할을 마치며, 특히 표면 기공율은 슬라이딩 조건(속도, 하중, 윤활)에 따라서 마멸특성이 우수한 최적이 영역이 존해할 것으로 판단된다.

• Journal of the Korean Ceramic Society
• /
• v.39 no.10
• /
• pp.919-927
• /
• 2002

In order to fabricate double-layered porous materials powders of different particle sizes were pressed stepwise. Ford＇s equation which predicts the fired density with the change in pressed density was employed in order to adjust the difference in sintering shrinkage of the green body with double-layered porous structure. Double-layered porous materials were characterized by investigating microstructures and permeability. SEM micrographs showed the distinct difference in pore sizes of double-layered porous material. Permeability of single-layered porous material increased by increasing the starting particle sizes and porosity as well. Permeability of the double-layered porous material depends largely on the layer of small pore diameter.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.14 no.2
• /
• pp.90-100
• /
• 1994

Ultrasonic velocities are widely used in the investigation of material properties. In this paper, a micromechanics model and the ultrasonic velocity were used to develop a nondestructive method to determine the density variation due to porosity in structural SiC. The micromechanics model developed can consider the pore shape and orientation. The model also takes into account the interaction between pores so that it can be applied to the material with high porosity content. A contact pulse overlap method was used to measure the ultrasonic velocities of porous SiC samples, and there was a linear correlation between the velocity and density (or porosity). Using the model and the measured velocity, the bulk density can be easily calculated. The calculated density was in good agreement with that obtained by Archimedes' method.

• Korean Journal of Materials Research
• /
• v.2 no.2
• /
• pp.85-94
• /
• 1992

The size, morphology and distribution of pores which affect on the physical properties of thermal barrier coatings were investigated to find the relationship with spraying parameters. The plasma-sprayed zirconia coatings contained numerous micropores as well as macropores which were appeared as spherical and irregular pores, and cracks. The pore formation process and its characteristics were varied with spraying distance. Porosity itself was varied with spraying parameters such as spray gun current, gas flow rate and the gas used(Ar or $N_2). The Porosity of coatings was ranged from 10 to 18% with the variation of spraying conditions. The relative hardness measured by the scratch test, showed strong dependence on the porosity of coatings rather than spraying parameters.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.11a
• /
• pp.474-476
• /
• 2006

본 연구에서는 다양한 두께, loading 및 기공 구조를 갖는 MPL을 형성하여 DMFC용 확산층을 제조하였다. 본 실험에서 제조한 확산층의 경우, 두께가 증가하면서 기공이 micro-pore에서 meso-pore 영역으로 옮겨감을 확인할 수 있었으며, 또한 기공구조에 따라 공기 투과도 특성이 변화하는 것을 확인할 수 있었다 각각의 확산층은 서로 다른 운전 조건에서 우수한 성능(흑은 안정적인 성능)을 갖는 것으로 확인되었으며, 이는 용도에 따른 확산층의 적합한 구조 설계가 요구됨을 의미한다.

• Clean Technology
• /
• v.28 no.3
• /
• pp.249-257
• /
• 2022

The adsorption equilibria of nitrogen on a region of nanoporous carbonaceous adsorbent with local molecular orientation (LMO) were calculated by grand canonical Monte Carlo simulation at 77.16 K. Regions of LMO of identical size were arranged on a regular lattice with uniform spacing. Microporosity was predominately introduced to the model by removing successive out-of-plane domains from the regions of LMO and tilting pores were generated by tilting the basic structure units. This pore structure is a more realistic model than slit-shaped pores for studying adsorption in nanoporous carbon adsorbents. Their porosities, surface areas, and pore size distributions according to constrained nonlinear optimization were also reported. The adsorption in slit shaped pores was also reported for reference. In the slit shaped pores, a clear hysteresis loop was observed in pores of greater than 5 times the nitrogen molecule size, and in capillary condensation and reverse condensation, evaporation occurred immediately at one pressure. In the LMO pore model, three series of local condensations at the basal slip plane, armchair slip plane and interconnected channel were observed during adsorption at pore sizes greater than about 6 times the nitrogen molecular size. In the hysteresis loop, on the other hand, evaporation occurred at one or two pressures during desorption.